It is common practice to set the knives in woodworking machine cutter heads to a height corresponding to that of a discharge work surface of the machine. Wood stock being processed is then fully supported as it is passed over the cutting knife and across the discharge surface.
With the stock supported on the discharge working surface the cutting depth of the knife is limited and the knife produces a smooth uniform surface. It is, however, critical that the knife cutting edge be perfectly aligned to the discharge working surface so that after the knife has cut the stock, the stock will be adequately supported by the discharge surface in the same plane as the knife cutting edge and no further cutting will occur.
The operator selects the depth the knife is to cut by pre-setting the feed side working surface at an appropriate depth below the level of the discharge working surface. The difference between the height of the two surfaces becomes the depth of cut when the knives are properly set.
Due to the frequent need to change knives for sharpening, cleaning, etc., it is very desirable to be able to quickly set the alignment of knife cutting edge to the discharge working surface. In the past a variety of jigs or setting gauges have been used for this procedure.
Machines such as jointers, which employ standard cutter heads, are manufactured in various cutting widths. The recent introduction and popularity of solid carbide and carbide topped knives, in addition to heavy industrial grade cutting knives adds to the difficulty in re-setting knives in the cutter head.